PHP - Require() && Regenerate_session_id() && Http Cookies

Php Folks,

As you know, typing the same code over and over again on all files is daunting.

I was wondering, if I can have an error_reporting.php file and then put:

include('error_reporting.php');

at the top of all my php files as header, where the error_reporting.php would have this content:

	<?php
	error_reporting(E_ALL);
ini_set('error_reporting','E_ALL');
ini_set('display_errors','1');
ini_set('display_startup_errors','1');
?>
	

Q1. Is that ok or not ?

Q2.

Usually, I have a conn.php with content like this:

	<?php
	$conn = mysqli_connect("localhost","root","","db_database");
$db_server = 'localhost';
$db_user = 'root';
$db_password = '';
$db_database = 'test';
$conn->set_charset('utf8mb4');//Always use Charset.
	if (!$conn)
{
    //Error Message to show user in technical/development mode to see errors.
    die("Database Error : " . mysqli_error($conn));
    
    //Error Message to show User in Layman's mode to see errors.
    die("Database error.");
    exit();
}
	?>
	

And then, on all my php files, I just reference to the conn.php by putting the following line on the header:

	include('conn.php');
	

Or:

	require('conn.php');
	

And on each php file, just before dealing with mysql, I have a line like this:

	mysqli_report(MYSQLI_REPORT_ALL|MYSQLI_REPORT_STRICT);
$conn->set_charset("utf8mb4");
	

Now, I am wondering, why should I write the above 2 lines on all my php files that deal with mysql ? To keep things short, why don;t I just add those 2 lines in the error_reporting.php ? So, it looks like this:

error_reporting.php

	<?php
ini_set('error_reporting','E_ALL');//error_reporting(E_ALL);
ini_set('display_errors','1');
ini_set('display_startup_errors','1');
	mysqli_report(MYSQLI_REPORT_ALL|MYSQLI_REPORT_STRICT);
$conn->set_charset("utf8mb4");
?>
	

Shall I do this or not ?

This is a two part question... my previous post was surrounding an issue with Sessions, now I was told that it may be a server side issue so I contacted my host provider who said to me that sessions cookies REQUIRE https?? now this can't be valid because I've had no issues with sessions prior to this week - second part of this is, is there something I'm missing with maybe an updated versions? 

PS: yes, i'm new and simply trying to learn...